FXO port (red light): For the connection of PSTN lines or FXS ports of traditional PBX. MyPBX users could make or receive calls via FXO port.
FXS port (green light): For the connection of analog phones.
BRI port (orange light): For the connection of ISDN BRI lines. MyPBX users could make or receive calls via BRI port.
Note: The sequence number of the ports corresponds to that of the Indicator lights in the front panel. (I.e. the LED lights in the front indicate the connection status of the corresponding ports at the front panel.)